Principles of Biology: Mitosis - Essay Example

?Principles of Biology: Mitosis XYZ Section: UVW Magazine/ Journal: eLife Publication 20 Feb, of Article: Mitosis: Developing cell biology Page Number: p 1 - 3 Author (s) Name: Daniel Needleman Synopsis: Cell division is a basic phenomenon of life in living organisms. It is known that the process of cell division, irrespective of the animal species, remains invariably the same. It is here that we comprehend that despite being the different in their outward appearance this basic phenomenon invariably remains the same. In byline, the author of the article, Daniel Needleman, has said that experimentation has been able to understand the difference that exists in this cell division phenomenon among the animals. This difference is found out to reside on the chromosomal and molecular level rather on higher level view. This difference can also exist even between similar organisms. Over a long period of time, it was known that spindle fibers that segregate chromosomes during cell division show great variation in size and shape, but the underlying reason was not discovered. Experiments have shown that the embryos that undergo the process of division, after repeated division cycles, considerably reduced in size and so did the spindle sizes. The experiments conducted on organisms like mouse have revealed many facts yet it has been difficult to ascertain any explicit cause to the phenomenon. Thus, another aspect that is attributed with the change is the change in biochemistry during the course of cell division. To infer a proximal result of the obvious phenomenon, a causative analysis is used as help. Cellular biology research has, therefore, evaluated a relationship during the course of development, between protein and phenotype. They are known to be rudimentary elements in the research, thus disturbing one can produce a change in the other co-existing part of the combination. Spindles are basically composed of microtubules that are in turn composed of protein tubulin. Here we can comprehend the phenomenon of reduction in the size of spindles i.e. depletion of these protein tubilins. To be sure about the phenomenon, Wilbur and Heald of University of California at Berkeley, devised an experiment to understand what causes this reduction. This experiment is multistage causal analysis procedure (Wilbur and Held). Embryos are subjected to tests during different stages of their development. It revealed that the change in size of spindles was not caused by division rather it was related to the state of cytoplasm. This in turn puts a question mark on how cytoplasm produces such change. To answer this question a categorization of the same microtubules was made. Early stages revealed less de-polymerization or catastrophe to these microtubules, as compared to those in the late stages. This revelation through stag-wise analysis did not reveal the true picture that could be able to answer above mentioned questions. Varying lengths of microtubules during the de-polymerization cannot be understandable reason. Later Wilbur and Heald used another approach to understand the size variation of spindles. Cytoplasm and its effects on elementary protein structures of spindles were analyzed. Proteins responsible for microtubule catastrophies in different extracts were identified as Kinesin-13 and Kif2a. Kif2a was thought to be the reason of change in spindle sizes but extracts have revealed that concentration of this type of proteins remains constant during all stages of development. A co-existing phenomenon of importin-alpha attaching to the membrane or leaving the cytoplasmic area caused kif2a to be more active, that in turns increases microtubule catastrophy rates. (Wilbur Heald, 2013) Suggestion about this mechanism is perhaps understandable with the help of biochemistry, as with change in size due to successive divisions cause greater surface to volume ration than in larger cells. The only point in this understandable phenomenon is that why importin-alpha tends to be sequestered with the cell membrane during later stages. To be succinct about the phenomenon, it can be said that the changing biochemistry of cytoplasm causes change in size of spindles and it is perhaps an astounding conclusion. (Needleman 2013) Analysis: The author, Daniel Needleman has taken a causal analysis for the finding the reason for changes that occur in the size of spindles, during the course of continuous cell divisions. It is important here to mention that the reasoning is based on causal analysis that uses approximation. The clear picture of the phenomenon of change in the size of spindles during the later stages has been attributed to two probable causes; first relates the microtubule de-polymerization to the change in size, while the other one pertains to the change in activity of special proteins. The author has taken different approaches to ascertain the causes. But in fact the conclusion is perhaps an open ended argument. The author has not tried any eclectic approach that is commonly seen today in scientific inquiry methods. To describe the hypothesis he has used certain experiment results with variables that do not show typical variation during the course of propagation of stages. For example, it is seen that the concentration of certain micro-tubular proteins remains the same during early and later stages. This cannot be termed as sole basis for the conclusion. Although the author has recognized this fact, and invited and concluded that further experimentation can reveal more comprehension to understanding the phenomenon, but there has been no summing up of the causes and no eclectic approach towards fact finding analysis. The author has explained the slack or missing information that has, as yet, impeded total comprehension of the long known phenomenon of change in size of spindles. The factorial analysis is still point of discussion, as the author has stated in the concluding paragraph. The author has realized that whether the differences in spindles structure primarily caused by one or two factors, or are there more unknown factor that should be involved in answering the question. This analysis is understandable because in scientific studies objective approach is the only way to understand phenomenon Cell biology also uses empirical results. If experimentation can result in achieving certain conclusions, then there should be no probable or causal explanations. Determinists are of the same view and thus this perspective of comprehending natural sconces should be used to make clear explanation of the real causes for the change in size of the spindles. Intellectual Benefit (Evaluating the Article): From the article it is revealing that following two approaches, to comprehend biological bases of events, are being used in natural sciences, namely, causal analysis approach and candidate approach. In these approaches change in one variable is keenly observed to note change in any other factor or variable. In causal analysis, what causes what is noted, whereas, in candidate approach, change is immediate surroundings are noted for any sort of change in the object under observation. Another benefit of the article was to understand how cellular organisms are subjected to analysis. Their compositional elements and factors are subjected to experimentation. As in this article the basic protein structure of spindles was noted. Then the categorization of these proteins was analyzed with their co-occurring elements. This can be seen in the case of protein and phenotype analysis. This analysis resulted in a conclusion that phenomenon of de-polymerization occurs due to repeated divisions of the cells. This division causes depletion of tubulin that constitutes the micro-tubule structure of proteins. The analysis of the author has concluded in a very convincing way. It stated the probability of multi factorial reasons for the change in spindle sizes. It further explained that MCAK an type of protein category may have variable activity level at different stages. This MCAK activity is attributed to the increase in catastrophy changes that depletes tubulin causing reduction in size. The author has also helped, readers, bring home to the point that approximation needs further studies so as to clearly ascertain the cause. References Needleman, Daniel. "Developing cell biology | eLife." eLife | The open-access journal for outstanding advances in life science and biomedicine, backed by the funders of research. Harvard University, United States, 19 Feb. 2013. Web. 20 Apr. 2013. Wilbur, Jeremy D. "Mitotic spindle scaling during Xenopus development by kif2a and importin ? | eLife." eLife | The open-access journal for outstanding advances in life science and biomedicine, backed by the funders of research. N.p., 19 Feb. 2013. Web. 20 Apr. 2013. Read More